Obesity is a major and increasing health problem in the United States. While many interventions have resulted in short-term weight loss, few programs exist that support successful maintenance of a healthy body weight, and fewer still are generalizable to a primary care population. Obesity tends to be a chronic, lifelong condition and relapse after weight loss is common. Despite the fact that obesity is associated with a host of medical diseases, weight interventions are usually conducted in a vacuum, divorced from the participants' usual medical care and without the input from the primary care team. Therefore, there is a great need for interventions that can assist with long-term maintenance of healthy body weight in the general population and in persons with existing medical conditions. Furthermore, such efforts should be linked to ongoing medical care. Our research team has developed an intervention - Virtual Lifestyle Management (VLM) - that successfully uses health information technology (HIT) to promote weight loss among primary care patients. We now propose to extend our work to evaluation of HIT tools designed to promote weight maintenance and prevent relapse in primary care patients who have successfully lost weight. Our proposal leverages recent developments in HIT, such as online visits and electronic health records, which enable primary care sites to contact patients and track their progress in ongoing weight maintenance efforts. We propose a randomized clinical trial - Maintaining Activity and Nutrition through Technology-Assisted Innovation in Primary Care (MAINTAIN-PC) - to test whether online tracking tools and weight maintenance coaching visits for patients and real time electronic progress reports for primary care providers (PCPs) [Continued Coaching (CC)] will support more successful weight maintenance than online tracking tools alone [Tracking Only (TO)] in a group of primary care patients who have lost e 5% of their body weight. The online coaching visits for participants will be delivered through the primary care site's electronic patiet portal (HealthTrak) and the electronic progress reports for PCPs delivered through the electronic health record (EHR). Our proposed intervention has a sound theoretical framework, incorporating both the Chronic Care Model and principles related to successful behavioral weight loss programs: self-monitoring, support, problem solving, and relapse prevention. By focusing on weight maintenance and relapse prevention, increased collaboration with primary care, and integration with existing HIT systems and tools, we will extend our previous work and fill a crucial gap in the successful treatment of obesity as a chronic medical condition.